Inserted blade cutter



Feb.19, 1946. F. P. MILLER 2,395,287

INSERTED BL ADE CUTTER Filed June 30-, 1945 Z SheetS-Sheet 1 FRANK ma 6R Feb. 19, .1946. F. P. MILLER I INSQERTED BLADE CUTTER Filed June so, 1943 2 Sheets-Sheet 2 Patented Feb. 19, 1946 UNITED STATES PATENT OFFICE INSERTED BLADE CUTTER Frank P. Miller, Meadville, Pan; Robert W. Thomas and Florence G. Miller, executors oi. said Frank P. Miller, deceased, assignors to Robert W. Thomas, Meadville, Pa.

Application June 30, 1943, Serial'No. 492,929

(Cl. fill-e105) Claims.

This invention relates to the art of rotary cutters of the inserted blade type and is concerned principally with means for locking blades in position when mounted in blade receiving and holding slots provided in the cutter body. An effective means for accomplishing this purpose comprises some form of radially disposed locking screw threaded into a socket in the cutter body in operative relation to the blade, either with or without the intermediary of a wedge member, whereby to impart a lateral wedging force that increases in magnitude as the screw is advanced and clamps the blade firmly against the back or trailing wall of its holding slot. In such installations the effective period of service is determined by the degree of durability of the screw socket threads; when these become worn, or if they are damaged or stripped, the entire cutter body has to be scrapped. The cutter body, which is the most valuable element of the organization, cannot practicably be hardened sufficiently to guard against damage or wear of the socket threads.

An object of the invention is to provide an improved means for mounting a blade locking screw in a cutter body, whereby a replaceable bushing having hardened threads is utilized as a socket for the screw.

Another object is to provide a blade bearing wedge in complemental association with the bushing for increasing the area of pressure contact against the blade.

Still another object is to provide means for preventing lateral displacement of the wedge into the blade slot in the absence of the blade while at the same time permitting removal and insertion of the wedge axially with respect to the bushing.

A further object is to provide an improved arrangement of blade holding slot and back-up screw for efiecting endwise adjustments of the blade and also for absorbing end thrust when the blade is subjected to heavy loads as in making deep cuts.

Other objects will be apparent to those skilled in the art.

In the accompanying drawings:

Figure l is a fragmentary face view, partly in section, of a cutter body with blades secured therein in accordance with the invention.

Figure 2 is an elevation thereof.

Figure 3 is a section taken on the line 3-3 of Figure 1.

Figure 4 is asection taken on the line 5-4 of Figure 1.

Figure 5 is a perspective view, partly in section,

of a blade holding slot with its associated bushing and wedge; the wedge being shown as in position for insertion in place.

Figure 6 is an exploded perspective of the looking screw socket assembly of bushing and wedge.

Figure 7 is an enlarged sectional view of an assembly of locking screw, bushing, wedge, and blade as mounted in a cutter body.

Figure 8 is a sectional detail view similar to Figure 7 but illustrating an alternative form of wedge.

Figure 9 is a perspective view of the wedge shown in Figure 8.

Figure 10 is a sectional view of a blade positioned in its holding slot in engagement with a back-up screw.

' Figure .11 is a section taken on the line lI-l l of Figure 10.

Figure 12 is a section taken on the line 12-12 of Figure 10.

Figure 13 is a perspective view, partly in section, of a blade holding slot and back-up screw.

In the practice of the invention as illustrated herein, a rotary cutter body I4 is provided with peripherally arranged slots l5 for receiving and holding the cutter blades IS. The slots may open at their front ends to the front face of the cutter but have closed inner U-shaped ends terminating inwardly of the rear face of the cutter whereby to provide a thick .rear wall ll at the inner end of each slot. The trailing side wall of each slot is longitudinally serrated to engage complemental serrations on the trailing face of the cutter blade to provide for radial adjustment of the blades with respect to the axis of the cutter, and the leading face of each blade is provided with serrations running to the bottom edge of the blade for a purpose to be explained.

Adjacent the leading face of each blade, the cutter body is cylindrically bored to provide a circular socket or bore I8 having an axis approximately radial to'the cutter and walls parallel to the axis of the socket. This arrangement of socket is preferred as the socket is formed in one operation and without lateral movement of the forming tool. The axis of the socket is so spaced from the leading wall of the blade slot that the plane of the wall comprises a chord of the socket circle, with the socket opening into the slot as best shown in Figure 5 to form an aperture having a width approaching but less than the diameter of the socket. The major portion of the socket is occupied by a bushing segment l9 provided with an internal hardened thread 20. The hardened bushing thread is capable of withstanding wear and is not susceptible to stripping or other damage, and in this manner the highly desirable feature of a hardened threaded socket is obtained for the locking screw without the necessity of hardening the entire cutter body. The bushing is provided with notches 2| into which small portions of the body material are peened for removably securing the bushing in place.

The threaded bore of the bushing is tapered to receive a complementally tapered locking screw 22 having in its head a tool engageable recess 23 whereby the screw may be operated to advance or retract it. Preferably, but not necessarily, the locking screw and its threaded bushing bore are tapered in the manner illustrated in my prior United States Patent No. 2,128,571 of August 30, 1938; that is, the axis of the bushing bore is at an angle with respect to the plane of the leading wall of the blade slot and inwardly convergent relative thereto, and the pitch line of the bore threads is parallel to the bore axis with the bottoms of the threads having flat surfaces increased in area approaching the inner end of the bore, so that the bore is tapered with respect to the line of the bottom of its threads although the pitch line of its threads remains parallel to the bore axis. correspondingly, the pitch line of the threads on the locking screw is parallel to the screw axis and tapering is eifected by increasingly grinding on the tops of the threads as the leading end of the screw is approached to produce a taper on the tops of the screw threads corresponding to the taper of the threaded bushing bore. The

screw is slightly smaller in diameter than the 7.

threaded bore so that as the screw is advanced toward the bottom of the socket itis moved bodily laterally to compound its wedging action in securing a blade in the slot.

Associated with the locking screw and bushing is a wedge member 24 that complements the bushing segment to fill the socket l8 when the wedge is inserted therein. It will be noted that the wedge is retained against displacement laterally into the blade slot when the blade is removed by the radiusof the socket l8 which narrows the wedge recess as it approaches the blade slot, so that the wedge cannot fall into the slot.

The wedge is provided with a tapered groove or recess 25 cooperating with the bore of the bushing l9 to complete therewith an encircling socket for the locking screw. The depth of the groove 25 is uniform throughout so that the bottom of the groove is parallel to the leading face of the adjacent blade. This arrangement allows the axis of the tapered screw and bushing to swing inwardly toward the blade so that the space occupied by the wedge, screw, and bushing is reduced as it approaches the bottom of the blade. This is especially desirable as it permits close arrangement of a large number of blades in the cutter body. A tool engageable notch 26 is provided in the bottom edge of the wedge so that it may be lifted out of the socket I8 with facility by a hooked implement,

The back or blade engaging face of the wedge is formed with serrations Z'Lcomplemental to the serrations 28 on the leading face of the cutter blade. The engagement of these serrations locks the blade against longitudinal movement in its slot under end thrust force and also provides means whereby the blade may be held in positions of adjustment longitudinally of the slot. [The use of these interengagingwedge and blade serrations may, however, be dispensed with as illustrated in Figure 7, where the bearing surface of 'wall of its slot.

greatly the applied holding force.

the wedge and front face of the blade are both flat.

The alternative embodiment of wedge member shown in Figures 8 and 9 is identical with that previously described except that it has in addition a bottom web providing a lateral shoulder 29 which engages beneath the bottom of the locking screw to prevent the wedge from falling radially out of its recess when the screw is loosened.

. In the embodiment of the invention illustrated in Figures 10, 11, 12, and 13, a back-up screw 30 is employed to adjust the blade in its slot and to absorb end thrust to which the blade may be subjected in service. The back-up screw operates in a threaded bore 3| opening from the rear face of the cutter body through the rear end wall I! of the slot with the bore threads being continued in the side walls of the slot. This arrangement provides an exceptionally sturdy mount for the back-up screw as it has thread bearing in the cutter body as 'well as in the slot walls. Further, the curved or rounded rear end formation of the slot provides additional thread bearing area.

' When a blade is adjusted to proper position in its receiving slot with the bushing, wedge, and

locking screw assembled in the adjacent socket recess 18, as the screw is threaded home its taper forces the wedge member into increasingly tight bearing engagement laterally against the blade and clamps the blade firmly against the trailing The wedge member distributes the clamping force over a much greater area of the blade than would be possible if the screw bore directly upon the blade, and thus increases The wedging action of the locking screw is compounded by the additive effects of the convergence of its axis with respect to the blade and the taper of the screw and bushing.

The invention herein shown and described is capable of variation in structural detail and farra-ngement of parts, and it is to be understood that any such variations may be made that are comprised within the scope of the invention as claimed. r l

I claim: 7

1. In an inserted blade cutter, a body having therein a blade slot, a blade in the slot, a tapered locking screw adjacent one side of said blade, an internally tapered and threaded socket member mounted in said body and receiving said screw, the axes of said socket member and screw being inwardly convergent to the plane of the blade, a bodily laterally movable wedge member between said screw and blade in bearing contact with both 'and having a groove forming a socket portion for the screw, and the bottom of said parallel to the plane of the blade.

In an inserted blade cutter, a body having a blade slot therein,- a blade in the slot, a recess in the body adjacent the blade slot and opening thereinto, an internally threaded bushing segment removably seated in said recess opposite its opening to the blade slot, a wedge member in sertable, in said recess between the bushing and blade slot, said wedge member having a contact portion engageable with and parallel to the blade, the width of said wedge member being greater groove being than that of the recess openingto the: blade: slot, said wedge member having a groove in registry with the bushing and of uniform depth: from end to end, the bottom of said groove-being parallel to, the plane of the blade, the threads of said bushing being tapered on an axis inwardly convergent to the plane of the blade, and a tapered locking screw in threaded engagement with said bushing for bearing upon the groove of said wedge member to wedge said member against the blade as the screw is advanced toward the bottom of the bushing.

3. In an inserted blade cutter, a body having a blade slot therein, a blade in the slot, a recess in the body at one side of the blade slot and opening thereinto, a bushing segment seated in said recess opposite its opening to the blade slot, a wedge member in said recess between said bushing and the blade slot, said wedge member having a contact portion engageable with and parallel to the adjacent blade face, said bushing being internally threaded on an axis inclined relative to the plane of the blade, a tapered locking screw in threaded engagement with said bushing and bearing on said wedge member to force the same laterally against the blade, and a shoulder on the bottom of said wedge member engageable beneath the locking screw to retain the wedge member against longitudinal movement outwardly of the bushing.

4. In an inserted blade cutter, a body having a blade slot therein, a blade in the slot, a cylindrical recess in the body at one side of the blade and on an axis inclined to the plane of the blade, said recess opening into the blade slot, an internally threaded bushing occupying a portion of said recess, a wedge member occupying the remaining portion of said recess, said wedge member having a tapered groove of uniform depth and the bottom of the groove being parallel to the adjacent face of the blade, the threads of said bushing being tapered on an axis inclined relative to the plane of the blade, and a locking screw threaded in said bushing in bearing engagement with the wedge member groove, the threads of said screw having a pitch line parallel to the screw axis and the tops of said threads being progressively and increasingly flattened off approaching the entrant end of the screw whereby to provide increased bearing contact against said wedge member.

5. An inserted blade cutter including a body, a blade slot extending into said body from a surface thereof, said slot having opposed parallel sides, a blade in said slot with corresponding parallel sides, an elongated bore extending into said body from said surface adjacent one of the parallel sides of said blade and opening into said blade slot, a portion of the inner wall of said bore being generally cylindrical but inwardly tapered and at least semi-cylindrical in extent, said portion being screw-threaded, a tapered screw threaded in said bore, a wedge member between said screw and blade, filling the space between said screw, the remaining bore wall, and blade, said wedge member including a recess defined by a smooth unthreaded wall of a curvature corresponding to that portion of the screw not engaged by said bore Wall portion, and the axes of said screw and bore being at such an angle with respect to said blade, that the side part of the screw adjacent the blade is parallel to said parallel side of the blade, and that part of the wedge member located between the screw and the blade and including the bottom of the recess, is of equal thickness from end to end with its sides adjacent the said side part of the screw and the blade being parallel to the said parallel blade side.

FRANK P. MILLER. 

